Centris Bees and White Ratanay in the Tucson Mountains

Krameria grayi – White Ratany is a grayish inconspicuous desert bush that grows in the lower elevation of the Tucson Mountains  Even when it's blooming, they are not very showy, though the single flowers and later the heart shaped seed pods are very pretty and intricate.

But right now, during their blooming season the bushes draw attention not through their looks but by the noise coming from them. Loud, deep buzzing, very sonorous, very different from the higher sound of Honey Bees.

Big Centris bees are coming and going, sometimes hovering with a strange wiggling motion, sometimes landing in the sand nearby - seemingly just resting.

These New World bees range with 250 species from Kansas to Argentina, and here around the Tucson Mountains I have found at least 3 species. Females of these bees possess adaptations for carrying floral oils rather than (or in addition to) pollen or nectar. According to Wikipedia, they visit mainly plants of the family Malpighiaceae to collect oil, but also Plantaginaceae, Calceolariaceae, Krameriaceae and others. Yesterday, they were definitely concentrating on that one blooming Kramericea, the Ratanay.

Some also visited Janusia, Fam. Malpighiaceae. I did not know the family of this strange vine, but obviously I can rely on the good senses of the bees and in this case Wikipedia (I think I know who is the careful editor of these bee entries).

The Centris bees  completely ignored a desert lavender bush in direct proximity. These flowers were later in the day extremely popular, but with honey bees.

Centris Subgenus Paracentris, Oil-Diggers and Desert-Diggers, Female, could be C. cockerelli or atripes

I have watched Centris pallida  dig tunnels and nesting chambers into loose sand and J. Alcock describes the same for another sympatrically occurring Sonoran Desert Centris, C. rhodopus. So I expect this Centris bee to behave similarly. 
I asked Entomologist and pollination expert Doug Yanega how the oil is used in the nest to rear the larvae. Here is his answer:

'The nest cells are vertical and they have a lining that prevents the oil seeping into the soil, and the bees just scrape off the liquid (which is rather viscous) into the cell.
Once they have a good pool, they float an egg on top and seal it. There are numerous bee genera that do this worldwide, but in the US I think only Macropis and Centris, IIRC.

P.S. Today I found this C. cockerelli  on our neighbor's hybrid (Desert Museum) Palo Verde. There is no sign of C. pallida yet, but most of the foothills paloverdes are not blooming yet around Picture Rocks. I just learned from Doug Yanega that there are no oils in Parkinsonia - just nectar that the bees need to feed themselves. I guessed that already because I often see male Centris on those flowers.

As for the species identification of the Rantanay Centris: One suggestion was C. caesalpinia, but they have red eyes, which mine did not.  Not C. rhodofus because they have red eyes and legs. Mine look like C. cockerelli, except that those should have yellow faces, and mine have a reddish orange clypeus. But:
 John Ascher When all else fails, consult the literature! Turns out that there is a western form in CA and AZ of C. cockerelli with a reddish yellow clypeus and an eastern form form in TX with a white to yellowish clypeus intergrading in NM. I had forgotten about this. So C. cockerelli is likely correct. Sorry for the confusion. At least we learned something (if nothing else, to consult the literature rather then rely on memory!)
 So: western form of Centris cockerelli!

Mysterious piles of silvery grains in the desert

I like my social media connections very much, even if I do spend much too much time with them. On Facebook, BugGuide and Flickr I am connected to many knowledgeable experts in their fields and creative artists whose work I would otherwise never get to see.
I bring in my own contributions by helping local friends to solve their bug mysteries and identify the occasional lizard or bird.
A couple of weeks ago, I ran into a mysterious 'thing' myself. Actually, I found 'it' by kicking over a long dried cow pie, left in the state land behind our property by cattle that was moved out years ago. But I still find the occasional bug or banded gecko hiding in those places ...

This time the ground under several pies was covered with a grainy silver gray substance. The grains were very regular in size. In my macro photos they also appeared sculpted or textured. There were tiny silver fish running between them.

Silver fish eggs? No, every female lays up to 100 in her live time. It would have taken a village or a small town of silver fish to produce this many.

I put the image on Facebook rather than BugGuide because I wasn't sure that this had anything to do with insects.
Rich Hoyer immediately suggested seeds.

After the monsoon the desert was covered in a golden blanket of chinch weed. It's still blooming.   Many plants are already setting their papus-equipped fruit.

There would have been enough chinch weed seeds to collect, but those seeds are long and dark. After knowing what to look for I actually found about three of them among thousands of the shorter ones. There is one in the bottom right corner.

So what are the little grey seeds? James Trager suggested mint or euphorbia. After searching for a long time I came up with one plant that is probably in the mint family, but it is by far too uncommon.
Euphorbia then?

 I sent the photo to Tom VanDevender who has a seed collection for the Sky Island Alliance. I had even discovered a seed pod in one of my photos by now. Yes, they are euphorbia seeds and can the alliance please keep the nice photo for their files? Sure.

 But now I wanted to know the exact species. There are patches of a small brownish green, prostrate weed all over, but I had completely ignored it because it is so unremarkable and common. Does it even flower? Of course. I just needed a magnifying glass to see flowers and even little seedpods.

Probably Chamaesyce/Euphorbia micromera

 Actually, I soon recognized that there were two species around and posted photos of both on FB.  FB friend Burr Williams from Texas then linked my query to the young botanist Nathan Taylor who actually specializes in 'prostrate euphorbia species' and who was glad and excited to help!

Chamaesyce/Euphorbia abramsiana

 He not only identified the two spp from our state land but also a third that had been in my files because of a bee fly that uses its tiny flowers.

Euphorbia/Chamaesyce albomarginata with Hemipenthes lepidota Cochise Co. AZ

So now think we know that the grainy stuff is indeed Euphorbia seeds, but how did it get under the old cow pie? Many FB friends speculated. The idea that the cow fed on the plant and then somehow segregated the seeds to expel them in a dense layer seemed unlikely. Also the seeds were fresh and the cow gone for years. It also wasn't wind drift that had piled up, because the cow pie was still sticking to the ground before I kicked it.

Of course, any collection of small seeds suggests ants. Many plants actually equip each seed with a little treat called elaiosome,, so ants will carry the seeds to their nests, eat the treat and throw out the seed, still intact (Seed dispersal by ants (myrmecochory).
Our two great collectors in the area are Veromessor pergandei and  Pogonomyrmex rugosus. But none of them seemed to be around in the vicinity of the cow dung. Also, both species tend to bring their harvest to their nests rather the storing it somewhere else.  

Under many dry cow pies, there are colonies of Solenopsis xyloni (Southern Fire Ant) a little ant that I only knew as a fierce predator. But James Trager told me that they also collect seeds. So I went through my pictures again. Yes! There are the little guys working among the seeds, and there even seems to be an entrance to a deeper more subterranean part of their nest on the left side. Remember that the entire seed pile was originally under ground, or at least under a very old piece of cow dung.

There, mystery solved! Net working and discussing worked. Except: what are those amber colored seeds? we thought that they were gray ones that had lost a waxy outer coating. looking more closely, I do not think so anymore. So? Suggestions?

The Night of the Desert Queen Peniocereus greggii

Last night the flowers on our backyard Queen of the Night (Peniocereus greggii) finally opened. The flowers were small but perfect. They seemed to glow in the light of the full moon and their sweet fragrance floated on the humid, warm air of this monsoon night.

 A single small moth was visiting. Even at my black light, this still is a moth-poor time. Last year I noticed that many queen flowers wilted away without producing fruit. The reason could have been a lack of pollinators. But last night I found a longhorn beetle obviously doused in pollen. I'm sure he came to the sweet smell and found the nectar and will also distribute the pollen.

I went back in the very early morning hours to find more blooming plants. The first thing I noticed was that our backyard flowers had already closed up, usually a sign that they are pollinated.

I walked across about half a square mile of state trust land. Many of the plants that were blooming last year were resting this season. The wild native Queen cacti whose branches are thin and not very succulent rely mainly on  big underground tubers for survival during droughts. After a year with many flowers and fruit, the above-ground stems often shrivel and dry up. New sprouts emerge from the ground but rarely bloom for the first two years.

But I found about a dozen new plants that I had not known before. Many were small and had only a single flower, but some were as tall as I, with big, antler-shaped stems and up to a dozen flowers.
Of course the pollinators may be drawn to the flowers by the sweet fragrance, but I, being a visual creature, scan the area for the pale white spots that barely clear the branches of the creosote bushes. The color seems perfect to reflect the uv part of the lunar spectrum. So the big mobile sphinx moths can probably also do a long distance visual scan, even at night.

This morning however, I found even the wilting flowers inundated by honey bees that were obviously still getting their fill. Every plant was surrounded by dozens of honey bees. This is very different from last year, when I found little Agapostemon sweatbees but no Apis melifera at all.
I think I know the explanation: the winter of 2012/13 brought several nights of deep freeze. Well provisioned honey bee hives in Europe are able to keep the temperatures high enough during cold spells to allow the majority of bees to survive. Africanized honey bees usually sustain much greater losses. Small feral hives (many Africanized bees tend to split hive and swarm more frequently than Italian honey bees) are even less cold resistant. So while Africanized bees can usually survive Arizona winters as feral colonies, the winter of 2012/13 had pretty much wiped out the local population. But now, after the very warm winter of 2013/14, they are back in force.
The Queen of the Night is by timing and color the very opposite of a bee flower, but those feral honey bees have great scouts and are fast learners - I think they found all the wilting flowers today and carried off all the drags.    

 

I did not ask any dogs to join me on my NBC quest, but after a while I noticed that Cody had quietly joined me. We walked all over together, until he finally got tired of my meandering from plant to plant. He might have felt too weak to go on and returned home as quietly as he had come out. This was our last walk together and the photo above is the last one I took of our most beloved dog. A week later, Cody died.

Backyard pollinators in March

Our patio garden - a mix of local and exotic early bloomers

It's March, and the 'garden' part of our property is erupting in color. We plant a few exotics like aloes close to the house.  They are succulent low water-users from Africa, so they do well here in Arizona. Hummingbirds, Gila Woodpeckers and Verdins love them, but as most imported flowers, they are rather useless for our endemic insects.

Anthophora sp. female at Penstemon flowers, their specialty. Photo Terry Stone

Anthophora sp. males visit the flowers rarely, and always early in the morning

In our backyard the exotics are mixed with locals like Penstemon, Brittle Bush and Creosote Bushes that are all in full bloom too. Each species is visited by a distinctly different group of endemic bees and flies.

Only Honey Bees go wherever they find pollen and nectar. They are imported from Europe and the Middle East, also from Africa, so no wonder that they like Aloes flowers

Andrena male (right) approaching a presumed female

On the yellow Brittle Bush discs, several species in the mining bee genus Andrena are extremely active. They were  nearly completely missing last year after a severe freeze in late February. I am not saying that the bees had not survived, but their usual synchronization with the Brittle Bush bloom was totally off. Instead, last year we saw an abundance of Sand Wasps, that are usually much rarer.

Sand Wasp Steniolia sp.

 After this very warm winter the Andernas are back in their usual high numbers. Especially the males contribute to the buzz around the bushes. They try to mate with everything of the right size. Pairs in copula are nearly impossible to photograph because most mating attempts end in an undignified tumble off the flower.

mating Andrena pair

Mating flies are much easier to capture, even though the next example is a tiny fruit fly. There are several species in this group, like the Sunflower Seed Maggot Fly, that lay their eggs into the developing seeds of composite flowers.

Euarestoides acutangulus

Several species in the syrphid genus Copestylum were feeding on  Brittle Bush nectar, among them the huge Mexican Cactus Fly that is a convincing Carpenter Bee mimic.

Palpada furcata,                   Copestylum mexicanum (Mexican Cactus Fly),                     Eristalis sp.

 Most Copestylum species in Arizona lay their eggs in dead or injured cacti so their huge maggots can develop in the unlimited resources of for example a decaying saguaro.

Copestylum avidum

 The pair in the photo was actually flying around together and probably wasn't planning to use the perfectly healthy little Christmas Cholla as a larval host. 

Eupeodes volucris (Bird Hover Fly)

Here is another syrphid fly. While the adults of Eupeodes volucris also like nectar, they are also drawn by aphid populations on the flower stems. Aphids are the main food of the larvae.

Nomada sp

Any place where many insects that collect and store food for their offspring regularly appear, like here Mining and Honey Bees, attracts also brood predators that want their kids to go along for the ride. These may lay eggs on the flowers or on captured males or females of the target species, or the parasite follows them home to then throws her own eggs into the open nest entrance. They are often related bees like the Nomada species above (Cleptoparasites of Andrena and others).

Eupompha elegans

Lytta auriculata (Red-eared Blister Beetle)

Blister beetles also lay their eggs on the underside of flowers hoping that their hatchling larvae will find their way into a bee's nest by hitching a ride on a flower-visiting adult. Lytta auriculata showed up for the first time on our Brittle Bush.

Anthrax vierecki

Hemipenthes sp.

Bee fly females can often be seen hovering over the entrance of a ground bee nest, tossing their eggs into it in a characteristic forward thrust.

Mecaphesa sp. Flower Crab Spider

Of course the flower visitors are also assaulted by a number of direct predators that are waiting close to the nectar sources. I would have completely overlooked the flower crab spider in its camouflage if I hadn't seen the contrasting spec of its prey.

Zelus renardii (Leafhopper Assassin Bug)

Ambush bugs may be much better hidden on flowers by color and shape than this assassin bug Zelus renardii, but her leafgreen color and stealthy approach give her a wider hunting range.

So I am looking forward to our Brittle Bush bloom every spring, and I don't mind at all that we find more young plants every year. They only grow on the artificial patio elevation anyway, I suspect that the caliche layer under the undisturbed soil does not agree with them. They pretty much dry up during between April and mid July and come alive again during the monsoon.

By the time the Brittle Bush flowers are drying up and the gold finches are beginning to investigate them for seeds, the first cacti are blooming, usually Beavertail Prickly Pear and Arizona Hedgehog.

Augochlorella sp. on
Echinocereus pentalophus

But this year the Lady Finger Cactus (Echinocereus pentalophus) has beaten them by a couple of days. Little green sweat bees, Augochlorella sp. are buzzing the flowers

 Even after the flowers are all wilted, Brittle Bush still offers something to the local bee population: Megachile Leafcutter Bees are cutting the tapestry for their nest chambers from the leafs.

Mating season for backyard raptors

Prairie Falcon photo by Ned Harris

This morning we watched an aerial ballet high in the sky above our backyard. A falcon was soaring, but with his feet hanging down, then banking, spreading his tail feathers, diving a little, catching himself again...I first thought that it was a Kestrel hunting insects. But when Randy brought my binoculars I recognized it as a bigger bird, a Prairie Falcon. He kept circling, diving and banking for more than 5 minutes and was finally joined by his partner. They circled together and then sped up towards Panther Peak.

 We don't seem to have an American Kestrel pair in our saguaro this year, but we sometimes hear  mating calls and see the male fly over. They are probably nesting in the State Land to the north.

Our Dark Female, the Red-tailed Hawk, has flown over a couple of time too, and now she is settling in the Saguaro nest that she used two years ago, she seems to alternate nests regularly. Both sites are along a wash in the state land, only about 300 feet apart.

Great Horned Owls are hooting at night from the Twin Peak on the east side of our land. We found a dead one this winter, but there must be a resident pair again.
 We also found a dead adult Harris Hawk. We have no power lines here that could electrocute them. I hope they aren't dying from an environmental poison. High in the food chain, raptors are always at risk.   

The Cooper's Hawks are also getting territorial. For the first time ever I saw the female go very aggressively after a juvenile Red-tail that likes to hang around.
We also have a ghost, a silver grey male Northern Harrier, but he only visits regularly every winter and then disappears for the breeding season.
With all those raptors getting ready to breed, we are hoping for enough rain to keep the land green and productive. But does the next storm have to hit right during my next art show in Dove Mountain? On my birthday???